1. Field of the Invention
The present invention relates to a simultaneous two-way communication apparatus using an ear microphone, incorporated in which are: a microphone or pickup mechanism for picking up bone conduction sounds (i.e., vibrations) in a user's external auditory meatus; and, a sound-pressure type speaker unit.
2. Description of the Related Art
Due to its howling problem, the ear microphone capable of performing the simultaneous two-way communication is restricted in sound volume of its received sound. In other words, the ear microphone has no problem when used in a noiseless environment, but encounters difficulties in communication when used in a high-noise environment. Such difficulties often makes it substantially impossible for the user to use the ear microphone. Especially, most of the ear microphones each using an acceleration type pickup unit have their resonance points in a frequency range of from about 2 to about 5 KHz, and, therefore are apt to raise howls in use.
As described above, in the ear microphone, particularly, in the simultaneous two-way communication type ear microphone using the acceleration type pickup unit, there is found the howling problem. Due to its howling problem, the simultaneous two-way communication type ear microphone is not capable of sufficiently increasing in sound volume its received sound, and, therefore disadvantageous in this respect.